致谢：本文档参考了，表示崇敬的谢意。

闲话不表，直接上菜。

/*
*file:   WifiControl.h
*desp:   power on/off wifi device by "SetDevicePower" way
*/

#ifndef _WIFICONTROL_H_
#define _WIFICONTROL_H_

#include <PM.h>
#include <Winreg.h>

class WifiControl
{
public:
/// <summary>
/// 类构造函数, 主要功能是从注册表中获取到wifi的设备描述串
/// 此串是以"HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Power\State\{98C5250D-C29A-4985-AE5F-AFE5367E5006}\"打头的
/// 如果是背景灯，则直接赋 m_tsDevice 值为"TEXT("BKL1:")"
/// </summary>
WifiControl()
{
   ZeroMemory(m_tsDevice, MAX_PATH);

   HKEY hKey = NULL;
   LPCTSTR lpSubKey=_T("System\\CurrentControlSet\\Control\\Power\\State");
   LPCTSTR lpKeyValueHead = _T("{98C5250D-C29A-4985-AE5F-AFE5367E5006}\\");

   if (ERROR_SUCCESS != RegOpenKeyEx(HKEY_LOCAL_MACHINE, lpSubKey, 0, KEY_READ, &hKey))
    return;
  
   DWORD dwIndex = 0;
   DWORD dwMaxPath = MAX_PATH;
   DWORD dwType = 0;
   while (RegEnumValue(hKey, dwIndex++, m_tsDevice, &dwMaxPath, NULL, &dwType, NULL, NULL) != ERROR_NO_MORE_ITEMS)
   {
    if (NULL != wcsstr(m_tsDevice, lpKeyValueHead))
     break;

    ZeroMemory(m_tsDevice, MAX_PATH);
    dwMaxPath = MAX_PATH;
   }

   ::RegCloseKey(hKey);
}

/// <summary>
/// wifi设备是否开启
/// </summary>
/// <returns>TRUE:开启;FALSE:未开启</returns>
BOOL IsEnabled()
    {
        CEDEVICE_POWER_STATE s = D4;
        if (m_tsDevice [0])
        {
            GetDevicePower(m_tsDevice, POWER_NAME, &s);
        }
        return s == D0;
    }

/// <summary>
/// 给wifi设备加电或断电
/// </summary>
/// <param name="bEnable">TRUE:加电;FALSE:断电</param>
/// <returns>参考:ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.chs/wceddk5/html/wce50lrfSetDevicePower.htm</returns>
HRESULT Enable(BOOL bEnable)
    {
        if (m_tsDevice [0])
        {
            return SetDevicePower(m_tsDevice, POWER_NAME, bEnable ? D0 : D4);
        }
        else
        {
            return ERROR_DEVICE_NOT_AVAILABLE;
        }
    }

protected:
WifiControl& operator=(const WifiControl&)
{}

WifiControl(const WifiControl&)
{}

private:
    TCHAR m_tsDevice[MAX_PATH];
};

#endif

以上是 SetDevicePower 方式，是OK的；其实还有一种 SetPowerRequirement 方式，此种方式由电源管理器执行加电断电，电源管理器有其自身的一套供电策略，在wo的测试过程中发现：
1。如果操作WIFI，SetPowerRequirement是不行的。
2。如果操作背景灯，当灯为亮时，SetPowerRequirement断电没反应；当灯为灭时，SetPowerRequirement加电正常
以下是 SetPowerRequirement 方式的背景灯操作：

/// <summary>
/// SetPowerRequirement方式的背景灯设备加电断电,事件通知给电源管理器(power manager),由其负责执行
/// </summary>
/// <param name="bBacklightOn">布尔型,TRUE:加电;FALSE:断电</param>
void SetBacklightPowerRequirement(BOOL bBacklightOn)
{
// 背景灯设备描述串
TCHAR tszBacklightName[] = TEXT("BKL1:");
static HANDLE s_hBacklightReq = NULL;

if (bBacklightOn)
{
   if (NULL == s_hBacklightReq)
   {
    s_hBacklightReq = SetPowerRequirement(tszBacklightName, D0, POWER_NAME | POWER_FORCE, NULL, 0);
   
    if (!s_hBacklightReq) RETAILMSG(1, (L"SetPowerRequirement failed: %X\n", GetLastError()));
   }
}
else
{
   if (s_hBacklightReq)
   {
    if (ERROR_SUCCESS != ReleasePowerRequirement(s_hBacklightReq)) RETAILMSG(1, (L"ReleasePowerRequirement failed: %X\n", GetLastError()));

    s_hBacklightReq = NULL;
   }
}
}